The present invention relates in general to a conveyor for transporting articles over a predetermined distance and path, and more particularly, to a conveyor commonly referred to as a powered belt turn for transporting articles along a curved path which includes a counterbalance guide assembly to prevent the radial-inward displacement or drifting of the conveyor belt during use.
A variety of conveyor systems are known for transporting various articles, such as packages, crates and the like from one location to another in manufacturing and other distribution operations. These conveyor systems include straight sections or curved sections where the conveyor system changes direction, as well as article raising and lowering sections. Curved conveyor sections can be inexpensively constructed from a plurality of rotatable rollers which support the article being conveyed, such as known from U.S. Pat. No. 2,990,052. One disadvantage in using roller type conveyors about a curved section is the inability of the conveyor to maintain a predetermined orientation of the article as it advances along the curved section. This results from the article sliding along the rollers in a manner which causes the article to twist and turn as it is being advanced. As a result, the article frequently reaches its final destination in an orientation which is not proper for the manufacturing or other distribution operation to be performed.
In solving this orientation problem, it is known to use power driven endless belt conveyors about curved sections. The power driven feature of these conveyors also has the additional advantage of conveying articles which are relatively heavy, and which might otherwise stop or slow down on the aforedescribed roller type conveyor systems. This is particularly important in conveyor systems where the articles must be conveyed at a uniform rate of linear speed through various straight and curved sections.
Presently, known power driven curved conveyors utilize various devices for maintaining the curved conveyor belt in proper position while it is being advanced around the curved path. In this regard, it is known that the endless belt has a tendency to drift radially inward while being advanced. Known devices for maintaining the proper orientation of the endless belt include the use of guide chains mounted on one or both sides of the conveyor belt such as disclosed in U.S. Pat. No. 3,854,575. In other known arrangements, U.S. Pat. No. 3,044,603 includes a drive chain along the outer curved edge of the conveyor belt and is formed with spaced apart upstanding tongues which overlap and are secured to the outer edge of the belt. U.S. Pat. No. 3,901,379 discloses an arrangement in which the outer edge of the conveyor belt is provided with a bead which is guided between a pair of rollers. The axis of the rollers are arranged at an angle to one another in a manner such that the bead is compressed to prevent radial-inward drifting of the belt.
U.S. Pat. Nos. 4,846,338 and 4,202,443 disclose an arrangement in which the outer edge of the conveyor belt is attached to a peripheral drive chain by means of a bracket which supports a roller which is in contact with a guide rail. U.S. Pat. No. 3,951,256 discloses an arrangement which includes a series of rollers arranged on transverse axes attached directly to the underside of the conveyor belt and which are adapted to ride in separate transversely arranged guide channels on a conveyor support frame. These known guide devices and arrangements are relatively complicated in construction, resulting in increased cost of manufacture, as well as anticipated rapid wear requiring frequent adjustment or component replacement.
There is also known from FIG. 1 an arrangement which includes an endless conveyor belt 100 which is supported by a slider bed 102. A plurality of C-shaped brackets 104 are attached about the outer edge of the conveyor belt 102. The free ends of the C-shaped bracket 104 rotational support a pair of oppositely facing rollers 106 which engage a pair of guide rails 108 arranged on either side of the conveyor belt 100. A stationary cover 110 is mounted so as to enclose the upper portion of the C-shaped bracket 104 to prevent possible damage to the arrangement or injury to individuals. This arrangement is undesirable in that the C-shaped bracket 104 and cover 110 extend above the surface of the conveyor belt 100 which will interfere with the transporting of articles whose dimensions might exceed the width of the conveyor belt. This effectively limits the size of the articles which a given conveyor system will be capable of handling.